Tire pressure management system valve integrity verification method

ABSTRACT

A method of verifying the integrity of a valve in service in a tire pressure management system is disclosed. The method of verifying valve integrity of a valve interposed between a tire and conduit assemblies for conducting fluid to and/or from the tire in a tire maintenance system includes closing the valve for prohibiting fluid flow into the conduit assemblies in fluid communication with the valve and monitoring the pressure of fluid in the conduit assemblies in fluid communication with the valve for ascertaining a pressure increase therein.

BACKGROUND OF THE INVENTION

Conventional tire pressure management systems typically have centraltire inflation systems (CTI systems), also known as on-board inflationsystems and traction systems. These tire pressure management systems arewell known, as may be seen by reference to the following U.S. Pat. Nos.:5,516,379; 5,313,995; 5,273,064; 5,253,687; 5,180,456; 5,179,981;5,174,839; 5,121,774; 4,924,926; 4,922,946; 4,917,163; 4,893,664;4,883,106; 4,883,105; 4,825,925; 4,782,879; 4,754,792; 4,724,879;4,678,017; 4,640,331; and 4,619,303. The entire disclosure of each ofthese patents is incorporated herein.

Generally, tire pressure management systems employ a pneumaticallycontrolled wheel valve that is affixed to each vehicle wheel assemblyfor controlling tire pressure in response to pressure signals from afluid control circuit. The fluid control circuit is connected to eachwheel valve via a rotary seal assembly associated with each wheel valve.Tire pressure is monitored by means of a sensor that is positioned in aconduit assembly in the fluid control circuit. When the wheel valve andcertain control valves are opened, the pressure in the conduit assemblyequalizes to tire pressure which can be sensed by the sensor. Anelectronic control unit receives electrical pressure signals generatedby the sensor and appropriately controls the fluid control circuit inresponse thereto for inflating or deflating a selected tire.

Despite the advances gained in tire pressure management systems, whilein service, system failures can develop with potentially costly and/ordangerous consequences. Specifically, referring again to FIG. 2,although wheel valve assembly 30 eliminates a potential failure mode inthe supply lines between the supply and a tire by venting same, therebystemming line breakdown ordinarily occasioned from long-termpressurization, wheel valve assembly 30 becomes a potential failuremode. Failure of wheel valve assembly 30 could lead to rapid deflationof an associated tire 28, which could cause the imposition of anunbearable load on a weakened paired tire 28, thus ultimate failure of atire pair on one end of an axle. This could lead to loss of control ofvehicle 12 or damaging load shifting therein. What is needed is a methodof verifying the integrity of a valve, such as a check valve, in servicein a tire pressure management system.

SUMMARY OF THE INVENTION

The invention provides a method of verifying the integrity of a valve inservice in a tire pressure management system. The method of verifyingvalve integrity of a valve interposed between a tire and conduitassemblies for conducting fluid to and/or from the tire in a tiremaintenance system includes closing the valve for prohibiting fluid flowinto the conduit assemblies in fluid communication with the valve andmonitoring the pressure of fluid in the conduit assemblies in fluidcommunication with the valve for ascertaining a pressure increasetherein.

The invention provides improved elements and arrangements thereof, forthe purposes described, which are inexpensive, dependable and effectivein accomplishing intended purposes of the invention. Other features andadvantages of the present invention will become apparent from thefollowing description of the preferred embodiment, which refers to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail below with reference to thefollowing figures, throughout which similar reference characters denotecorresponding features consistently, wherein:

FIG. 1 is a diagrammatic view of a tire pressure management system for avehicle, a vehicle incorporating same being shown in dotted line;

FIG. 2 is a cross-sectional detail view of a conventional vehicle wheelassembly;

FIG. 3 is a schematic view of components of the system of FIG. 1; and

FIG. 4 is a schematic view of a flow chart for a method configuredaccording to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention is an apparatus for and a method of verifying theintegrity of a valve. Specifically, the invention verifies the, capacityof a valve to effectively prevent fluid from passing therethrough, suchas, for example, air escaping from a tire when a tire pressuremanagement system is not inflating or deflating vehicle tires.

FIG. 1 shows a tire pressure management system 10 for a vehicle 12 fordescribing, but not limiting applicability of the invention. Vehicle 12may be, but is not limited to being a tractor-trailer. The system may beused in connection with a wide variety of vehicles, includingautomobiles.

Vehicle 12 may include a plurality of axles, including a steer axle 14,a tandem axle assembly having drive axles 16, 18 and another tandem axleassembly having trailer axles 20, 22. As shown in greater detail in FIG.2, each axle, such as drive axle 14, may include wheels 24 affixed towheel hubs 26 disposed at each outboard end of the axle and rotationallysupported on axle 14. Each wheel 24 may include one or more inflatabletires 28 mounted thereon.

System 10 monitors and controls pressure within each tire 28 of vehicle12. System 10 may include wheel valve assemblies 30, a fluid source 32,a vacuum source 34, and a fluid control circuit 36. System 10 mayfurther include a plurality of pressure sensing circuits 38, one or morereceivers 40, one or more electronic control units 42, one or more loadsensors 44, a speed sensor 46, and an operator control device 48.

Wheel valve assemblies 30 are provided to control the flow ofpressurized fluid into and out of tires 28. Valve assembly 30 is mountedto each end of each axle and is connected to the remainder of system 10through a rotary seal connection 50. Wheel valve assembly 30 isconventional in the art and may include the wheel valve assemblydescribed and illustrated in U.S. Pat. No. 5,253,687 or U.S. Pat. No.6,250,327, the entire disclosures of which are incorporated herein.

Rotary seal assembly 50 also is conventional in the art and may includethe rotary seal assembly described and illustrated in U.S. Pat. No.5,174,839, the entire disclosure of which also is incorporated herein.

Referring again to FIG. 2, wheel valve assembly 30 may include an inletport 30 a coupled to a rotatable port 50 b of rotary seal assembly 50,an outlet port 30 b in fluid communication with the interior of tire 28,and an exhaust port 30 c, best shown in FIG. 1. Rotary seal assembly 50may further include a non-rotatable port 50 a connected to a conduit 52of fluid control circuit 36. Valve assembly 30 assumes a closedposition, as illustrated in FIG. 1, when the fluid pressure at inletport 30 a is substantially atmospheric, an open position connectinginlet port 30 a and outlet port 30 b when the fluid pressure at inletport 30 a is a positive pressure, and an exhaust position connectingoutlet port 30 b and exhaust port 30 c when the fluid pressure at inletport 30 a is a negative pressure.

Fluid source 32 provides positive pressurized fluid to system 10 andtires 28. Fluid source 32 is conventional in the art and may include apressure source, such as a pump 54, an air dryer 56, and a first fluidtank 58 connected via a conduit 60 to the brake system fluid tanks 62,64 and to the fluid control circuit 36 via a branch conduit 60 a. Checkvalves 66 prevent sudden loss of fluid pressure in brake tanks 62, 64 inthe event of upstream pressure loss. A pressure sensor 68 monitorspressure within tank 58 and provides a pressure indicative signal toelectronic control unit 42.

Vacuum source 34 produces a negative pressure in system 10 to decreasefluid pressure in tires 28 of vehicle 12. Vacuum source 34 also isconventional in the art and may include a vacuum generator 70 controlledthrough a solenoid valve 72. A low pressure zone is produced by passingfluid through a venturi like portion of vacuum generator 70. Upon urgingsolenoid valve 72 into an open position via a control signal fromelectronic control unit 42, a vacuum or negative fluid pressure,relative to atmospheric pressure, is introduced in a conduit 74, whichhas a small orifice 76 disposed proximate the low pressure zone producedby generator 70. Conduit 74 also is connected to a one-way vent valve 78for rapid venting of positive fluid pressure from conduit 74. Vent valve78 includes a valving member 80 that is drawn into a closed position inresponse to negative fluid pressure in conduit 74 and is urged into anopen position in response to positive pressure fluid in conduit 74.

Fluid control circuit 36 directs the flow of pressurized fluid withinsystem 10 for controlling pressure in tires 28 of vehicle 12. Controlcircuit 36 may include a pair of pressure control valves 82, 84 and aplurality of axle distribution valves 86, 88, 90. As shown, a singlefluid control circuit 36 controls pressure in all of the tires 28 ofvehicle 12. However, control circuit 36, and other portions of system10, may be replicated so that, for example, one control circuit 36 maycontrol tire pressures in the tractor portion of vehicle 12 and anothercontrol circuit 36 may control tire pressure in the trailer portion ofvehicle 12.

Pressure control valve 82 directs positive pressurized fluid from fluidsource 32 to tires 28 of vehicle 12. Valve 82 may include a conventionaltwo position-two way, solenoid controlled and pilot fluid operatedvalve. Valve 82 includes a valving member 92 that is spring biasedtoward a closed position, as shown in FIG. 1. Valving member 84 assumesan open position in response to energizing of a solenoid operativelyassociated therewith via control signals from electronic control unit42. Valve 82 has a first port 82 a coupled to a conduit 94 leading tofluid source 32. Valve 82 has a second port 82 b coupled to anotherconduit 96 leading to axle distribution valves 86, 88, 90.

Pressure control valve 84 vents control circuit 36. Valve 84 isconventional in the art and may also include a two position-two way,solenoid controlled and pilot fluid operated valve. Valve 84 includes avalving member 98 that is spring biased toward an open position, asshown in FIG. 1. Valving member 98 assumes a closed position in responseto energizing a solenoid operatively associated therewith via controlsignals from electronic control unit 42. Valve 84 has a first port 84 acoupled to conduit 74 leading to orifice 76. Valve 84 has a second port84 b coupled to conduit 96 leading to axle distribution valves 86, 88,90.

Axle distribution valves 86, 88, 90 limit the supply of positivepressurized fluid to, or the release of fluid from, the tires 28 of oneor more axles 14, 16, 18, 20, 22 of vehicle 12. Valves 86, 88, 90 areconventional in the art and may include two position-two way, solenoidcontrolled and pilot fluid operated valves. Valves 86, 88, 90 direct theflow of fluid to and from the tires 28 of axles 14, 16 and 18, and 20and 22, respectively. Each of valves 86, 88, 90 includes a valvingmember 100, 102, 104, respectively, that is spring-biased toward an openposition, as shown in FIG. 1, and which assumes a closed position inresponse to energizing a solenoid operatively associated therewith viaelectrical signals from electronic control unit 42. Each of valves 86,88, 90 respectively has first ports 86 a, 88 a, 90 a coupled to conduit96. Each of valves 86, 88, 90 respectively has second ports 86 b, 88 b,90 b leading to respective corresponding conduits 52, 106, 108 for eachaxle or tandem axle of vehicle 12.

Although axle distribution valves 86, 88, 90 are shown, individual tiredistribution valves could be used in conjunction with axle distributionvalves 86, 88, 90 or as an alternative to axle distribution valves 86,88, 90 to further control the flow of fluid to and from individual tires28 of vehicle 12. Further, although only three axle distribution valves86, 88, 90 are shown, the number of axle distribution valves may bevaried depending upon the number of axles of vehicle 12 and to allow forgreater individual control of the tires 28 of vehicle 12.

Pressure sensing circuits 38 monitor the tire pressure in each tire 28of vehicle 12. A variety of pressure sensing circuits 38 are known inthe art, such as the pressure sensing circuits described and illustratedin U.S. Pat. Nos. 5,600,301 and 5,838,229 assigned toSchrader-Bridgeport, International, Inc. Each circuit 38 may include apressure transducer 110 in fluid communication with the interior of avehicle tire 28. Each circuit 38 also includes a radio-frequencytransmitter 112 that transmits a parameter signal indicative of ameasured parameter associated with a corresponding tire 28 of vehicle12. Circuit 38 may be configured so that transmitter 112 transmitsparameter signals at a periodic rate or when a predetermined eventoccurs, such as a specific change in pressure level.

The parameter may be pressure or another value, such as tiretemperature, that may be indicative of tire pressure. The parametersignal preferably is encoded with a tire identification code to uniquelyidentify the particular tire 28 to which the signal corresponds. Theencoding of radio-frequency signals with unique identification codes iswell known in the art and may be implemented in a variety of ways knownin the art such as by frequency shift key modulation.

Receivers 40 receive the radio-frequency signals generated bytransmitters 112 of pressure sensing circuits 38 and provide electronicsignals to electronic control unit 42 corresponding to the receivedradio-frequency signals. Receivers 40 are conventional in the art andmay form part of control unit 42. The number of receivers 40 used insystem 10 may depend upon the number of vehicle tires 28, the locationof pressure sensing circuits 38 and other factors.

In the case of a tractor-trailer, multiple receivers 40 may be needed tomaintain signal integrity because of the relatively large distancebetween the tires 28 of the tractor-trailer and the relatively largenumber of tires 28. Where multiple receivers 40 are used, each receiver40 may be coupled to electronic control unit 42. Alternatively, severalsecondary receivers may be coupled through a hardwired, radio-frequency,or power lead communication connection to a primary receiver that iselectrically connected to the electronic control unit 42. The use of“wireless” connections between the primary and secondary receivers by,for example, the inclusion of radio-frequency transmitters in thesecondary receivers, enables different trailers to be secured to thetractor of vehicle 12 without requiring the decoupling and coupling of aplurality of electrical connections.

Referring to FIG. 3, electronic control unit 42 controls fluid controlcircuit 38. Control unit 42 may include a microprocessor operating underthe control of a set of programming instructions commonly referred to assoftware. Electronic control unit 42 may include a memory 114 in whichthe programming instructions are stored. Memory 114 also may containidentification codes for each tire 28 of vehicle 12 to uniquely identifythe particular tire 28 to which a particular parameter signalcorresponds. Memory 114 also may be used to record tire pressure valuesor user inputs over a period of time to assist in evaluating tirepressure management.

Control unit 42 may receive input signals from receivers 40, one or moreload sensors 44, speed sensor 46, and operator control device 48.Control unit 42 outputs a plurality of control signals to control valves82, 84, 86, 88, 90 of fluid control circuit 36 and solenoid valve 72 ofvacuum source 34. Control unit 42 also may generate a plurality ofoutput signals to a display device which may include a part of operatorcontrol device 48 or a freestanding device. The latter signals may beused to trigger the display pressure readings and or deflection levelsfor each vehicle tire 28, the load on vehicle 12 or a portion of it, andthe speed of vehicle 12. The signals may also be used to triggerwarnings to the operator of vehicle 12 in the event that pressure cannotbe maintained in one of the vehicle tires 28, the pressure exceeds orfalls below predetermined maximum and minimum tire pressure values, orthe pressure differs from a target pressure value by more than apredetermined amount.

Although a single electronic control unit 42 receives signals generatedby all of pressure sensing circuits 38 and generates control signals forall of valves 82, 84, 86, 88, 90 of fluid control circuit 36, more thanone electronic control unit 42 may be used. For example, one electroniccontrol unit may monitor pressure in tires 28 of the steer and driveaxles 14, 16, 18 of vehicle 12 and to control fluid pressure thereof,while a second electronic control unit may monitor pressure in tires 28of the trailer axles 20, 22 and to control fluid pressure thereof. Ifmultiple units are employed, a hardwired, radio-frequency, or power leadcommunication connection preferably is made between the units to allowsharing of information between the units and integrated control ofinput/output devices such as operator control device 48.

Load sensors 44 provide an indication as to the load on vehicle 12 and,consequently, tires 28 of vehicle 12, or the load on some portion ofvehicle 12 and, consequently, select tires 28 of vehicle 12. Loadsensors 44 are conventional in the art and load sensing may be providedin a variety of known ways, including through analysis of pneumaticpressure in the suspension of vehicle 12, analysis of powertrainparameters, the use of displacement transducers, or the implementationof load beams and strain gauges. Each load sensor 44 may provide one ormore signals to electronic control unit 42 indicative of the loadbearing on vehicle 12 or a portion thereof.

Electronic control unit 42 may initiate pressure adjustment in tires 28of vehicle 12 in response to signals from load sensors 44 in a varietyof ways. For example, electronic control unit may cause an increase ordecrease in the pressure in one or more tires 28 responsive to acorresponding increase or decrease in vehicle load based on a variety oflinear or non-linear functions. One or more tire deflection tables maybe stored in a memory, such as memory 114, and accessed by electroniccontrol unit 42 responsive to the signals from load sensors 44.

Speed sensor 46 measures the speed of vehicle 12 to further controldeflection levels for tires 28. High deflection levels can create safetyconcerns and reduce tire life if maintained while vehicle 12 isoperating at relatively high speeds. Speed sensor 46 is conventional inthe art and provides a signal to electronic control unit 42corresponding to speed.

Operator control device 48 may allow the operator of vehicle 12 to exertat least some level of control over system 10. Device 48 is conventionalin the art and may include a plurality of input/output devices, such asa keypad, touch screen, switches or similar input devices, and a displayscreen, sound generator, lights or similar output devices. Thus, device48 permits an operator of vehicle 12 to transmit control signals toelectronic control unit 42 to adjust pressure levels within the tires 28of vehicle 12. The control signals may, for example, correspond todeflection levels for tires 28 of vehicle 12. As a result, the operatoris able to adjust the deflection level of the tires 28 to correspond tothe terrain over which vehicle 12 is traveling. Such control isdesirable to provide improved floatation and traction on certainterrain.

Referring again to FIG. 1, the invention employs a sensor 200,preferably electronically integrated in control unit 42, for monitoringfluid pressure in the conduit assemblies of the fluid control circuit 36between the fluid and vacuum sources 32, 34 and the wheel valves 30.Sensor 200 may assume any form appropriate for measuring pressure in aconduit assembly. Sensor 200 may sense and respond to extant pressure inthe conduit assemblies, changes therein or other properties appropriatefor achieving the invention. Sensor 200 is configured to sense conduitassembly pressure changes and respond accordingly. Sensor 200 mayrespond to any of the foregoing properties by, for example, transmittinga corresponding signal to which control unit 42 is responsive.

Control unit 42 monitors or processes, rather than merely receives,input from sensor 200 at least when sensor 200 is in fluid communicationwith at least one valve assembly 30 and when system 10 is not inflatingor deflating any of tires 28. The sequencing and interaction ofcomponents of system 10, such as sensor 200 and control unit 42, may beappreciated more readily in the context of the following description ofthe present method.

FIG. 4 diagrammatically shows a flow chart of the present method. Themethod may be a routine called within the execution of a master tirepressure maintenance program (not shown).

At step S10, the invention provides for determining atmosphericpressure. Atmospheric pressure may be measured using sensor 200 uponclosing valves 82, 86, 88, and 90 and opening valve 84 to place theconduits of fluid control circuit 36 in fluid communication with outsideair. Alternatively, atmospheric pressure may be measured using aconventional dedicated pressure sensor (not shown) external to fluidcontrol circuit 36 and in communication with control unit 42. Themeasured atmospheric pressure value may then be stored in a memory ofcontrol unit 42. Control unit 42 then generates an offset value based onthe measured current atmospheric pressure to compensate absolutepressure values, such as a desired target tire pressure, referenced bycontrol unit 42 during tire pressure maintenance. Control unit 42 thenpasses control to step S15.

At step S15, the invention provides for determining the pressure intires 28. This may be achieved, for example, by polling any or all ofsensors 38 in tires 28, as described above, or other suitable process.Control unit 42 then passes control to step S20.

At step S20, the invention provides for determining whether a line leakfault exists. Control unit 42 evaluates whether a line leak flag was setby a line leak testing routine (not shown) which determines whether theconduit assemblies exhibit an incapacity to maintain fluid pressure, forexample, due to a rupture. If control unit 42 determines that a lineleak flag has been set, control unit 42 passes control along branch B10to step S30, described below. If control unit 42 determines that a lineleak does not exist, control unit 42 passes control along branch B15 tostep S25.

At step S25, the invention provides for determining whether the tiresare fully inflated. Control unit 42 compares the measured tire pressuresagainst an operator-configurable, or operator designated, targetpressure. If a measured pressure is less than the target pressure,control unit 42 determines that the tires are not fully inflated andpasses control along branch B20 to step S30, described below. If themeasured pressure is at least equal to the target pressure, control unit42 determines that the tires are at least fully inflated and passescontrol along branch B25 to step S35, as described below.

At step S30, the invention provides for inflating any or all of tires28. This may be achieved by any suitable method, such as by pressurizingthe conduit assemblies until the pressure therein is at least equal to atarget pressure. To this end, control unit 42 instructs solenoid 82 andany of control solenoids 86, 88 and/or 90 to open, and solenoid 84 toclose, thereby supplying pressurized fluid to tires 28, as describedabove, for a predetermined supplying duration. Following the supplyingduration, control unit 42 instructs conduit 82 to close, therebypreventing pressurized fluid from reaching any of control solenoids 86,88 and/or 90. Control unit 42 then passes control to step S35.

At step S35, the invention provides for venting the conduit assembliesfor an operator-configured, or operator designated, venting duration.The venting duration should be sufficient to allow the conduitassemblies to reach equilibrium with atmospheric pressure. As describedabove, control unit 42 vents the conduit assemblies by instructingsolenoid 84 to open, while any of control solenoids 86, 88 and/or 90 areopen, thereby enabling fluid communication between the conduitassemblies and valve 78. Because valving member 80 of valve 78 onlyopens in response to positive fluid pressure and closes in response toneutral or negative fluid pressure, valve 78 closes naturally when theconduit assemblies are at atmospheric pressure. After the ventingduration elapses, control unit 42 instructs solenoid 84 to close andisolate valve 78, thereby preventing further venting of the conduitassemblies. Lacking positive or negative fluid pressure at inlet port 30a, each valve assembly 30 should assume a closed position. Thus, absentpositive pressure toward a tire 28 or a vacuum for drawing fluid from atire 28, valve assembly 30 should remain closed and prohibit fluid frompassing from a tire 28 into the conduit assemblies. Control unit 42 thenpasses control to step S40.

At step S40, the invention provides, for determining the pressure in theconduit assemblies. Closing solenoids 82 and 84, yet leaving open any ofcontrol solenoids 86, 88 and/or 90 defines a fixed volume amongsolenoids 82 and 84 and one or more valve assemblies 30 caused to be influid communication therewith via open solenoid 86, 88 and/or 90. Thus,if a valve assembly 30 leaks, the conduit assemblies will realize acorresponding pressure increase. Sensor 200 senses and responds to thepressure increase. Control unit 42 registers the response of sensor 200.Control unit 42 then passes control to step S45.

At step S45, the invention provides for determining whether the gagepressure in the conduit assemblies is less than a limit. The limit maybe based on, for example, anticipated bleed or make-up air supplied tothe conduit assemblies to counteract inevitable conduit assemblyleakage, such as provided in the U.S. patent application Ser. No.10/004,762 filed contemporaneously herewith, which is incorporatedherein. The gage pressure measured in the conduit assemblies constitutesa pressure in excess of atmospheric pressure, or an absolute increase inpressure in the conduit assemblies since venting in step S35. Controlunit 42 compares the response of sensor 200, which is indicative of theconduit assembly pressure, with the limit. If the conduit assemblypressure is not less than the limit, potential exists for a failure of avalve assembly 30, therefore control unit 42 passes control along branchB30 to step S55, described below. If the conduit assembly pressure isless than the limit, valve assemblies 30 are deemed to be functioningproperly, therefore control unit 42 passes control along branch B35 tostep S50, described below. The limit is manufacturer-configurable, ormanufacturer designated.

At step S55, the invention provides for determining whether the conduitassembly gage pressure has exceeded the limit for a specified number ofconsecutive tests. Thus, if repeated inflations are followed by pressuredrops that exceed a predetermined limit, such is interpreted as afailure of a valve assembly 30. To this end, control unit 42 incrementsa counter and checks the updated value stored in the counter against aspecified value set by the operator. If the counter does not exceed thestored value, control unit 42 passes control along branch B40 back tostep S15, described above. If the counter exceeds the stored value,control unit 42 passes control to step S70.

At step S70, the invention provides for alerting the operator that avalve assembly 30 may have failed. Control unit 42 may set a lamp ortrigger other suitable alarm. Control unit 42 then passes control backto step S15, described above.

Step S50 is comparable to step S35, described above, thus described nofurther herein. Control unit 42 then passes control to step S60.

At step S60, the invention provides for clearing the counter describedwith respect to step S55 to avoid triggering a false alarm, for example,if control passes to step S55 for a first or other time less than aspecified number of times. Control unit 42 then passes control to stepS65.

At step S65, the invention provides for delaying initiating step S10 fora specified amount of time, such as 15 minutes. After the delay, controlunit 42 then passes control back to step S10, as described above, toagain ascertain the pressure status of tires 28 and valve assemblies 30,or check valves, associated therewith.

While the invention has been particularly shown and described withreference to the preferred embodiments thereof, it is well understood bythose skilled in the art that various changes and modifications can bemade in the invention without departing from the spirit and scope of theinvention.

1. Method of verifying valve integrity of a valve interposed between atire and conduit assemblies for conducting fluid to or from the tire ina tire maintenance system comprising: closing the valve for prohibitingfluid flow into the conduit assemblies in fluid communication with thevalve; monitoring the pressure of fluid in the conduit assemblies influid communication with the valve for ascertaining a pressure increasetherein; updating a counter when the pressure is equal to or greaterthan a pressure value; and initiating an alarm if the value of thecounter is equal to or greater than a count.
 2. Method of claim 1,wherein the pressure value is offset by an amount of pressureanticipated in the conduit assemblies from a make-up or bleed fluidsupply.
 3. Method of claim 1, wherein said initiating occurs within apredetermined time.
 4. Method of claim 3, wherein the predetermined timeis offset by an amount of time related to a rate of fluid supplyanticipated in the conduit assemblies from a make-up or bleed fluidsupply.
 5. Method of verifying valve integrity of a valve interposedbetween a tire and conduit assemblies for conducting fluid to or fromthe tire in a tire maintenance system comprising: closing the valve forprohibiting fluid flow into the conduit assemblies in fluidcommunication with the valve; monitoring the pressure of fluid in theconduit assemblies in fluid communication with the valve forascertaining a pressure increase therein; and, initiating an alarm whenthe pressure is equal to or greater than a pressure value; wherein thepressure value is offset by an amount of pressure anticipated in theconduit assemblies from a make-up or bleed fluid supply.
 6. Method ofverifying valve integrity of a valve interposed between a tire andconduit assemblies for conducting fluid to or from the tire in a tiremaintenance system comprising: closing the valve for prohibiting fluidflow into the conduit assemblies in fluid communication with the valve;monitoring the pressure of fluid in the conduit assemblies in fluidcommunication with the valve for ascertaining a pressure increasetherein; and, initiating an alarm when the pressure is equal to orgreater than a pressure value; wherein said initiating occurs within apredetermined time and the predetermined time is offset by an amount oftime related to a rate of fluid supply anticipated in the conduitassemblies from a make-up or bleed fluid supply.
 7. A method forverifying valve integrity of a wheel end valve, comprising the steps of:venting a conduit disposed between a fluid source and said wheel endvalve, said wheel end valve disposed between a tire and said conduit;determining the pressure within said conduit after said venting step;and comparing said pressure to a pressure limit corresponding to ananticipated pressure increase resulting from air provided to saidconduit from said fluid source to counteract fluid leakage in saidconduit.
 8. The method of claim 7, further comprising the step ofincrementing a counter if said pressure exceeds said pressure limit. 9.The method of claim 8, further comprising the step of comparing saidcounter to a predetermined amount.
 10. The method of claim 9, furthercomprising the step of initiating an alarm if said counter exceeds saidpredetermined amount.